Dynamic announcing for creation of wireless communication connections

ABSTRACT

Example electronic devices, including but not limited to implantable medical devices, and methods employing dynamic announcing for creation of wireless communication connections are disclosed herein. In an example, an electronic device includes a wireless communication interface to transmit announcement signals for creating a wireless communication connection with the external device. The electronic device also includes a sensor to detect a characteristic of an environment external to the electronic device, and a control circuit including an announcement timing control module to dynamically control timing of the announcement signals based on the detected characteristic.

PRIORITY CLAIM

The present application relates to and claims priority from U.S.provisional application Ser. No. 62/339,795, filed May 20, 2016,entitled “Dynamic Announcing For Creation Of Wireless CommunicationConnections,” which is hereby expressly incorporated by reference in itsentirety to provide continuity of disclosure.

FIELD OF THE INVENTION

The present invention relates to wireless communication technology. Morespecifically, the present invention relates to dynamically varyingannouncing frequency for creation of wireless communication connections.

BACKGROUND OF THE INVENTION

Many wireless communication technology standards, such as the originalBluetooth® standard and its variants (e.g., the Bluetooth Low Energy, orBLE, standard), facilitate creation of communication connections betweenpairs of devices using announcement or advertising data packets,messages, or other signals. In some communication standards, forexample, an electronic device may transmit such signals wirelessly whileIn an announcing or advertising mode (e.g., “discoverable” mode in theBluetooth (standard) to make nearby devices aware of the presence of theannouncing device. In response to those announcements or advertisements,another device may then attempt to create a communication connectionwith the announcing device by way of bidirectional exchange of deviceidentities and/or capabilities, encryption/decryption keys, and otherInformation with the electronic device to create a secure communicationconnection therebetween.

Typically, an electronic device is placed into its announcing oradvertising mode in response to some user input received via a userinterface, such as the press of a button or touch of an area on atouchscreen. However, some electronic devices that employ a wirelesscommunication technology either do not provide a tactile user interface,or simply cannot be accessed physically during normal operation. Onesuch class of device is the implantable medical device. Examples ofimplantable medical devices include, but are not limited to, automaticimplantable cardioverter defibrillators (AICDs), cardiac pacemakers,spinal cord stimulation (SCS) devices, deep brain stimulation (DBS)devices, and implantable loop recorders (ILRs), such as implantablecardiac monitors (ICMs) and subcutaneous atrial fibrillation (AF)monitors. Such devices often employ wireless communication to connectwith an external computer system to receive configuration information,commands, and so on, and to transmit operational status, logged events,and the like. Such devices, when implanted in a human body, are notphysically accessible, and thus do not provide a tactile or physicalinterface to facilitate placing the device into an announcing oradvertising mode to establish wireless communication with anotherdevice.

With the above aspects in mind, as well as others not explicitlydiscussed herein, various embodiments of an electronic device employingwireless communication, such as an implantable medical device, as wellas methods of operating such a device, are disclosed herein.

SUMMARY

In one embodiment, an electronic device may include a wirelesscommunication interface to transmit announcement signals for creating awireless communication connection with an external device separate fromthe electronic device. The electronic device may also include a sensorto detect a characteristic of an environment external to the electronicdevice, and a control circuit Including an announcement timing controlmodule to dynamically control timing (e.g., frequency) of theannouncement signals based on the detected characteristic. In someexamples, the electronic device may be an implantable medical device.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which depicts and describesIllustrative embodiments of the Invention. As will be realized, theinvention is capable of modifications in various aspects, all withoutdeparting from the scope of the present invention. Accordingly, thedrawings and detailed description are to be regarded as Illustrative innature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of an example electronic devicethat employs dynamic announcing for creation of wireless communicationconnections.

FIG. 2 is a simplified flow diagram of an example method of operatingthe electronic device of FIG. 1 to employ dynamic announcing forcreation of wireless communication connections.

FIG. 3A illustrates a system for the detection of environmentalconditions in communication with an external device through a wirelesscommunication connection.

FIG. 3B is a partly cut-away view of an example implantable cardiacstimulation device in electrical communication with at least three leadsimplanted into a patient's heart for delivering multi-chamberstimulation and shock therapy and for detecting environmentalconditions.

FIG. 4A is a functional block diagram of selected components of asubcutaneous implantable monitor of 3A, including an announcement timingcontrol module for dynamic announcing for creation of wirelesscommunication connections.

FIG. 4B is a functional block diagram of the example implantable cardiacstimulation device of FIG. 3B, Illustrating the basic elements providingpacing stimulation, cardioversion, and defibrillation in four chambersof the heart via one or more pulse generators, as well as anannouncement timing control module for dynamic announcing for creationof wireless communication connections.

FIG. 5 is a list of example announcement frequency factors that mayinfluence operation of the announcement timing control modules of FIGS.4A and 4B.

FIG. 6 is a list of example announcement frequency modes that theannouncement timing control modules of FIGS. 4A and 4B may provide basedon the announcement frequency factors of FIG. 5.

FIG. 7 is an example state diagram of the example announcement frequencymodes of FIG. 6.

DETAILED DESCRIPTION

This description is not to be taken in a limiting sense but is mademerely to describe general principles of the invention. The scope of theinvention should be ascertained with reference to the issued claims. Inthe description of the invention that follows, like numerals orreference designators are used to refer to like parts or elementsthroughout.

The following detailed description relates to electronic devices thatemploy a wireless communication interface. In one example, an electronicdevice may employ dynamic advertising (referred to herein as“announcing”) for creation of wireless communication connections withone or more other devices external to the electronic device via thewireless interface. In one example, the electronic device may alter thefrequency of announcement messages, data packets, or other signals thatare used to create a wireless communication connection. Alteration ofthe frequency may be based on one or more factors that may be accessedor sensed by the electronic device. In at least some examples, theelectronic device may be an implantable medical device, such as anautomatic implantable cardioverter defibrillator (AICD), pacemaker,spinal cord stimulation (SCS) system, deep brain stimulation (DBS)system, implantable loop recorder, or the like. In at least someexamples, the external device may be a smartphone, smartwatch, personaldigital assistant (PDA), tablet, laptop computer, desktop computer,bedside monitor, programmer, or the like.

As a result of at least some of the embodiments discussed in greaterdetail below, the electronic device may alter the frequency at whichannouncement messages or other signals are issued to balance overallpower consumption of the device with the amount of time consumed inestablishing a wireless communication connection when a physical userinterface to the device (e.g., a button, a touchscreen, or the like) isnon-existent or limited, thus at least restricting the ability of a userto place the device in an announcement mode explicitly. Morespecifically, announcement messages issued more often would reduce theamount of time to create a communication connection while increasingpower consumption, whereas issuing such messages less often would tendto produce the opposite effects.

In some devices currently employing Bluetooth® technology, a user mayinitiate the formation of a connection between devices by making atleast one of those devices “discoverable” by causing that device totransmit or broadcast one or more announcement or advertisementmessages. Such initiation may be in the form of a press of a button, atouch of a touchscreen area, or other direct physical contact with thedevice. The announcement messages may Include some identificationinformation of the device, some encryption key information, and/or soforth. A nearby device, in response to receiving one of theannouncements, may “pair” with the device providing the announcementmessages to exchange further encryption Information, data regardingcapabilities of the two devices, and so on. Based on that exchange ofinformation, the two devices may then be “bonded” to each other,facilitating one or more wireless communication connections between thedevices over any arbitrary time period until the devices are unbonded.

Further, some devices provide a Bluetooth® pairing mechanism by way ofthe Near Field Communications (NFC) technology protocol. In such cases,a user may bring a Bluetooth® device into contact or near-contact withanother Bluetooth@ device to pair the devices without the use of anexplicit announcement message phase.

In the situations described above, physical contact or near-contact witha device by way of a user or another device is utilized to initiate aprocess by which wireless communications are established betweendevices. In examples described more fully below, however, wirelesscommunication connections may be facilitated without such interaction.

FIG. 1 is a simplified block diagram of an example electronic device 200that employs dynamic announcing for creation of wireless communicationconnections. In this example, the electronic device 200 includes awireless communication interface 210 that may transmit wirelesscommunication signals to, and/or receive wireless communication signalsfrom, an external device 230, such as by way of an established wirelesscommunication connection 250. The wireless communication interface 210may Include wireless signal transmitters, wireless signal receivers,and/or other circuitry for providing functionality. In one example, thewireless signals conform to a wireless communication standard, such asBluetooth®, Bluetooth® Low Energy (BLE), ZigBee®, IEEE (Institute ofElectrical and Electronics Engineers) 802.15.4, MICS (Medical ImplantCommunication Service), MedRadio (Medical Device RadiocommunicationsService), or any other wireless communication standard that employspresence announcing or advertising to enable communication between atleast two devices, such as by way of establishing a wirelesscommunication connection between the electronic device 200 and theexternal device 230. U.S. Pat. No. 9,288,614 (Young et. al) and U.S.Pub. No. 2015/0065047 (Wu et al.), each of which is incorporated hereinby reference in its entirety, describe exemplary systems and methodsthat may be used in conjunction with the present invention to providefor initiating a bi-directional wireless communication connection 250between electronic device 200 and external device 230.

As depicted in FIG. 1, the electronic device 200 may also include awireless communication interface control module 220 that may providelogic and control functions to operate the wireless communicationinterface 210 according to the protocols or standards being used toperform the desired wireless communications. For example, the wirelesscommunication interface control module 220 may provide the logic forperforming the announcement messages, pairing, bonding, and connectioncreation of the Bluetooth® standards, as described above. In someexamples, the wireless communication Interface control module 220 mayinclude dedicated hardware circuitry to perform the desired functions.In other examples, the wireless communication interface control module220 may include one or more hardware processors, such asmicroprocessors, microcontrollers, digital signal processors (DSPs), orother algorithmic processors, along with one or more memory devicescontaining instructions executable by the one or more hardwareprocessors, to perform the functions ascribed to the wirelesscommunication interface control module 220. In yet other embodiments,the wireless communication interface control module 220 may include somecombination of dedicated hardware circuitry and programmable hardwareprocessor components.

Included within the wireless communication interface control module 220may be an announcement timing control module 222, which may access oneor more factors or parameters that indicate one or more aspects of theenvironment in which the electronic device 200 operates to determinedynamically when or how often one or more announcing or advertisingmessages, data packets, or other signals are to be transmitted tofacilitate creation of one or more wireless communication connections250 between the electronic device 200 and the external device 230.

External device 230 may include a patient activator to enable the user,such as a patient or caregiver, to manually trigger electronic device200 either to trigger an alert or trigger recording of EGM storage orother clinical episode, such as an episode of neuropathic pain,palpitations, or syncope.

FIG. 2 is a simplified flow diagram 300 of an example method 300 ofoperating an electronic device (e.g., the electronic device 200 ofFIG. 1) to employ dynamic announcing for creation of wirelesscommunication connections (e.g. the wireless communication connection250 of FIG. 1). While the method 300 is described below within thecontext of the announcement timing control module 222 of the wirelesscommunication interface control module 220 of the electronic device 200of FIG. 1, other circuits or systems may employ the method 300 in otherembodiments.

In the method 300, the announcement timing control module 222 may set aninitial frequency for transmission of announcement messages, datapackets, or other signals (operation 302). In some examples, thefrequency may be once every so many seconds or minutes, or may be zero(e.g., no announcement messages) for at least some periods of time.However, in other examples, the announcement timing control module 222may not set an initial transmission frequency for the announcements.

Thereafter, the announcement timing control module 222 may access one ormore factors or parameters that are to influence dynamically thefrequency of the announcements (operation 304). Examples of such factorsmay include, but are not limited to, the current time of day, currentand/or past environmental and/or operational conditions in which theelectronic device 200 is operating, the current announcement frequency,the current charge level of a battery or other energy source beingemployed by the electronic device 200 to perform its various functions,and so forth. Other factors, such as those that may be related to thespecific operations performed by the electronic device 200, may beutilized in other embodiments. The announcement timing control module222 may then determine whether a change in the announcement frequency iswarranted based on the accessed factors (operation 306). If so, theannouncement timing control module 222 sets a new, modified announcementfrequency based on the accessed factors (operation 308). Such updatingmay be performed on a periodic or repetitive basis. The announcementtiming control module 222 may then access the one or more factors(operation 304) to determine once again whether a new announcementfrequency is warranted (operation 306), continuing in such a mannerindefinitely.

While the operations 302-308 of the method 300 of FIG. 2 are illustratedin a particular order of performance, other orders for the operations302-308, including simultaneous, concurrent, and/or overlapping ofmultiple operations 302-308 are possible. For example, the accessing ofthe one or more factors (operation 304) may occur on a more-or-lesscontinual or repetitive basis, while the determining of the announcementfrequency based on those factors may occur concurrently, but less often.

Implantable medical devices serving as the electronic device 200 of FIG.1 will thus be described in conjunction with FIGS. 3A-B and 4A-B, inwhich the features included in various embodiments described hereaftercould be implemented. However, numerous variations of such a deviceexist in which various circuits and methods discussed below can beImplemented.

FIG. 3A illustrates a monitoring device 400, which may be implanted orexternal to the patient, and may dynamically communicate with anexternal device 230 using one or more wireless communication connections250. In certain embodiments, monitoring device 400 is a device capableof recording heart electrical activity such as an EGM-based monitor. Incertain embodiments, monitoring device 400 is a subcutaneous EGM-basedmonitor, such as an implantable loop recorder (ILR) (e.g., animplantable cardiac monitor (ICM) or a subcutaneous atrial fibrillation(AF) monitor). In certain embodiments, the ILR is subcutaneously (i.e.,just under the skin) Implanted in the chest of a patient to the left ofthe breastbone. An ILR may include two or more electrodes attached tothe casing or electrically connected to the device and spacedsufficiently far apart that cardiac events are sensed. An ILR that maybe used with the invention is, e.g., a SJM Confirm™ Implantable CardiacMonitor of St. Jude Medical. Examples of ILRs that may be used with theInvention are described in U.S. Pat. No. 8,241,221 (Park), U.S. Pat. No.8,467,884 (Park), and U.S. Pat. No. 7,294,108 (Bomzin et al.), each ofwhich is incorporated herein by reference in its entirety.

An ILR may begin recording heart electrical activity in response to, forexample, the ILR detecting electrical activity indicative of aheart-related problem, such as atrial fibrillation (AF), atrialtachycardia, ventricular tachycardia, asystole, syncope, and so on. Inother examples, the ILR may begin such recording in response toreceiving a signal from a patient-triggered external activator servingas the external device 230. Consequently, ILR operation may benefit froma dynamic increase in the announcement frequency to more quickly createa wireless communication connection 250 between the activator and theILR to allow the ILR to receive the signal from the activator based onone or more of the factors described herein, such as detection of anelevated heart rate, an arrhythmia, an increased or decreased level ofpatient physical activity, change in posture, time of day and/or thelike. As a result, the connection 250 may be established during timesassociated with a higher probability of the patient being symptomatic,and thus at times during which the signal from the activator is morelikely to be received.

In certain embodiments, monitoring device 400 is also a cardiacstimulation device, such as a subcutaneous implantable cardioverterdefibrillator (S-ICD) or a leadless pacemaker. An S-ICD may includemultiple subcutaneous extracardiac electrodes (also referred to asremote sensing electrodes) for detecting electrical cardiac signalswithin the chest of the patient. The subcutaneous extracardiacelectrodes are preferably extravascular and can be, e.g., paddleelectrodes or coil electrodes mounted subcutaneously outside of the ribcage, but are not limited thereto. Exemplary locations of thesubcutaneous extracardiac electrodes Include near the bottom of thesternum (slightly to the left), below the left pectoral area, and belowthe clavide and on the back left side (just below the shoulder blade).Of course, additional and/or alternative locations for subcutaneouselectrodes are within the scope of the present Invention.

Examples of S-ICDs that may be used with the invention are described inU.S. Pat. No. 7,970,473 (Nabutovsky, et al.), U.S. Pub. No. 2016/0030757(Jacobson et al.), and U.S. Pat. No. 9,320,448 (Xi et al.), each ofwhich Is incorporated herein by reference in its entirety. Examples ofleadless pacemakers that may be used with the invention are described inU.S. Pat. No. 9,278,218 (Karst et al.), U.S. Pat. No. 9,227,077(Jacobson at al.) and U.S. Pat. No. 8,798,745 (Jacobson et al.), each ofwhich is incorporated herein by reference in its entirety.

In certain embodiments, multiple monitoring devices 400 are used inconjunction with one another In a system and may communicate throughconductive communication, RF, or other wireless communication. Incertain embodiments, one of the monitoring devices 400 of a system ofmonitoring devices 400 is designated as a master device that gathersand, in some embodiments, processes communications from slave monitoringdevices 400 and communicates with an external device 230 using one ormore wireless communication connections 250. For example, a mastermonitoring devices 400 may be a S-ICD that communicates with a slavemonitoring device 400, such as a leadless pacemaker, through conductivecommunication, as described in, e.g., U.S. Pub. No. 2016/0030757(Jacobson et al.), incorporated herein by reference. The S-ICD maycommunicate with an external device 230 using a Bluetooth® interface oranother wireless communication interface implementing some wirelesscommunication protocol or standard.

FIG. 3B illustrates an implantable cardiac stimulation device 100 inelectrical communication with a patient's heart 12 by way of three leads20, 24, and 30 suitable for delivering multi-chamber stimulation and/orshock therapy. To sense atrial cardiac signals and to provide rightatrial chamber stimulation therapy, the device 100 may be coupled to animplantable right atrial lead 20 including at least one right atrial tipelectrode 22 that may be implanted in the patient's right atrialappendage. The right atrial lead 20 may also include a right atrial ringelectrode to allow bipolar stimulation or sensing in combination withthe atrial tip electrode 22.

To sense the left atrial and left ventricular cardiac signals and toprovide left-chamber stimulation therapy, the stimulation device 100 maybe coupled to a “coronary sinus” lead 24 designed for placement in the“coronary sinus region” via the coronary sinus ostium in order to placea distal electrode adjacent to the left ventricle and additional one ormore electrodes adjacent to the left atrium. As used herein, the phrase“coronary sinus region” refers to the venous vasculature of the leftventricle, including any portion of the coronary sinus, great cardiacvein, left marginal vein, left posterior ventricular vein, middlecardiac vein, and/or small cardiac vein or any other cardiac veinaccessible by the coronary sinus.

Accordingly, the coronary sinus lead 24 may be designed to receiveatrial and/or ventricular cardiac signals, deliver left ventricularpacing therapy using at least one left ventricular tip electrode 26 forunipolar configurations or in combination with a left ventricular ringelectrode for bipolar configurations, and/or deliver left atrial pacingtherapy using at least one left atrial ring electrode 27 as well asshocking therapy using at least one left atrial coil electrode 28.

The stimulation device 100 of FIG. 3B may also be in electricalcommunication with the patient's heart 12 by way of an implantable rightventricular lead 30 including, in this embodiment, a right ventricular(RV) tip electrode 32, a right ventricular ring electrode 34, a rightventricular coil electrode 36, a superior vena cava (SVC) coil electrode38, and/or so on. The right ventricular lead 30 may be insertedtransvenously into the heart 12 so as to place the right ventricular tipelectrode 32 in the right ventricular apex such that the rightventricular coil electrode 36 is positioned in the right ventricle andthe SVC coil electrode 38 will be positioned in the right atrium and/orsuperior vena cava. Accordingly, the right ventricular lead 30 may becapable of receiving cardiac signals, and delivering stimulation in theform of pacing and shock therapy to the right ventricle.

In certain embodiments, the implantable stimulation device 100 mayincorporate one or more optical sensors 3 (also referred to asphotoplethysmography (PPG) sensors) integrated with or attached to itshousing 40.

Optical sensors 3 may also be integrated with or attached to amonitoring device 400 (FIG. 3A) Implanted in the pectoral region of apatient. In certain embodiments, optical sensor 3 may be used to detectpatient interaction (as discussed in detail below). In certainembodiments, optical sensor 3 may be used to determine a person's heartactivity, and these measurements may be used in lieu of, or inconjunction with, electrical activity measurements. Changes in theoptical signal over time can be used to determine heart activity, evenif the position of the optical sensor is far removed from the heart. Insome embodiments, the monitoring device 400 may include both an opticalsensor and an EGM-based monitor. Optical sensors that may be used withthe current disclosure are disclosed in U.S. Pat. No. 8,328,728(Schecter), U.S. Pat. No. 8,478,403 (Wenzel et al.), and U.S. Pat. No.9,022,945 (Fayram et al.), each of which is incorporated herein in itsentirety. In other embodiments, the monitoring device 400 may include anEGM-based monitor and an impedance measurement circuit. Impedancemeasurement circuits that may be used with the current disclosure aredisclosed in U.S. Pat. No. 8,065,005 (Wong et al.) and U.S. Pat. No.9,265,436 (Min, et al.), each of which is incorporated herein in itsentirety.

The optical sensor, which can be used to obtain a PPG signal, includes alight source and a light detector. The light source 5 can include, e.g.,at least one light-emitting diode (LED), laser, incandescent lamp orlaser diode, but is not limited thereto. The light detector 7 caninclude, e.g., at least one photoresistor, photodlode, phototransistor,photodarlington or avalanche photodiode, but is not limited thereto.Light detectors are often also referred to as photodetectors orphotocells.

The light source 5 outputs light that is reflected, absorbed and/orscattered by surrounding patient tissue, and reflected/scattered lightis received by the light detector 7. In this manner, changes inreflected light intensity are detected by the light detector 7, whichoutputs a signal indicative of the changes in detected light. The outputof the light detector 7 can be filtered and amplified. The signal canalso be converted to a digital signal using an analog to digitalconverter, if the PPG signal is to be analyzed in the digital domain. APPG sensor can use a single wavelength of light, multiple discretewavelengths, or a broad spectrum of many wavelengths. If multiplewavelengths are used, the timing of the signals may be multiplexed todetermine optical response of tissue at different wavelengths.Additional details of exemplary implantable PPG sensors that may be usedin accordance with the present disclosure are disclosed in U.S. Pat.Nos. 6,409,675 and 6,491,639, both entitled “Extravascular HemodynamicSensor” (both Turcott), which are incorporated herein by reference.

It is generally the output of the photodetector that Is used to producea PPG signal. However, there exist techniques where the output of thephotodetector Is maintained relatively constant by modulating the drivesignal used to drive the light source, in which case the PPG signal Isproduced using the drive signal, as explained in U.S. Pat. No.6,731,967, entitled “Methods and Devices for Vascular Plethysmographyvia Modulation of Source Intensity,” (Turcott), which is incorporatedherein by reference.

Exemplary details of how to attach a sensor module to an electronicdevice 200 are described in U.S. Pat. No. 7,653,434, entitled“Autonomous Sensor Modules for Patient Monitoring” (Turcott et al.),which is incorporated herein by reference. It is also possible that theoptical sensor 3 be integrally part of the implantable stimulationdevice 100 or a monitoring device 400. For example, the optical sensor 3can be located within the housing 40 of an electronic device 200 thathas a window through which light can be transmitted and detected. In aspecific embodiment, the optical sensor 3 has a titanium frame with alight transparent quartz or sapphire window that can be welded into acorresponding slot cut in the housing of the implantable stimulationdevice 100 or monitoring device 400. This will Insure that theelectronic device 200 enclosure with the welded optical sensor willmaintain a hermetic condition.

Where the optical sensor is incorporated into or attached to animplanted electronic device, the light source and the light detector canbe mounted adjacent to one another on the housing or header of theelectronic device, or on the bottom of the device, or at any otherlocation. The light source and the light detector can be placed on theside of an electronic device that, following implantation, faces thechest wall, and are configured such that light cannot pass directly fromthe source to the detector. The placement on the side of the electronicdevice that faces the chest wall maximizes the signal to noise ratio bydirecting the signal toward the highly vascularized musculature, andshielding the source and detector from ambient light that enters thebody through the skin. Alternatively, at the risk of increasingsusceptibility to ambient light, the light source and the light detectorcan be placed on the face of the electronic device that faces the skinof the patient. The light source and light detector may be positioned toface each other at a distance apart. Other variations are also possible.

FIG. 4A is a functional block diagram of selected components of amonitoring device 400. The particular monitoring device 400 shown inFIG. 4A is for illustration purposes only, and one of ordinary skill inthe pertinent art could readily duplicate, eliminate, or disable theappropriate circuitry in any desired combination to provide an ECG orEGM-based monitor.

Housing 40 (shown schematically) of monitoring device 400 includes aconnector having one or more EGM sensor terminals 402 adapted forconnection to subcutaneous (SubQ) EGM sensors mounted to (or connectedto) the exterior housing of the device. Housing 40 (often referred to asthe “can”, “case” or “case electrode”) can also act as the return(common) electrode, or anode, for any sensing electrodes implantedseparately from the device. Only one EGM sensing electrode terminal isshown, but additional terminals can be provided to accommodateadditional sensing electrodes or sensing leads.

At the core of monitoring device 400 is a programmable microcontroller460, which controls heart activity detection, such as heart rate,morphology, heart rate variability, and arrhythmia, and event detection,such as myocardial infarctions, strokes, cardiac ischemia, and pain(whether due to angina or another underlying condition being monitoredand/or treated by the monitoring device 400 or another device in asystem). The microcontroller 460 includes a microprocessor, orequivalent control circuitry, designed specifically for detecting heartactivity and/or events and may further include RAM or ROM memory, logicand timing circuitry, state machine circuitry, and I/O circuitry.Typically, the microcontroller 460 includes the ability to process ormonitor Input signals (data) as controlled by a program code stored in adesignated block of memory. The details of the design and operation ofthe microcontroller 460 are not critical to the invention. Rather, anysuitable microcontroller 460 may be used that carries out the functionsdescribed herein. The use of microprocessor-based control circuits forperforming timing and data analysis functions is well known in the art.

A switch bank 74 includes a plurality of switches for switchablyconnecting the EGM electrodes (assuming there is more than one) to theappropriate I/O circuits, thereby providing complete electrodeprogrammability. A sense amplifier 482 is coupled to the EGM electrodesthrough switch bank 74 for sensing electrical cardiac activity. Senseamplifier 482 is capable of sensing signals In accordance with otherwiseconventional techniques. The switch bank 74 determines the “sensingpolarity” of the cardiac signal by selectively closing the appropriateswitches, as is also known in the art. In this way, the clinician mayprogram the sensing polarity. Sense amplifier 482 preferably employs alow power, precision amplifier with programmable gain and/or automaticgain control and/or automatic sensitivity control, bandpass filtering,and a threshold detection circuit, known in the art, to selectivelysense electrical signals of interest. The automatic gain control, ifimplemented, enables the monitoring device 400 to deal effectively withthe difficult problem of sensing any low frequency, low amplitude signalcharacteristics. The gain control is actuated by the programmablemicrocontroller 460. The gains are controlled on sense amplifier 482 bythe microcontroller using control line 486. The outputs of the senseamplifier are connected to microcontroller 460.

EGM signals and other sensed signals are also applied to the inputs ofan analog to digital (A/D) data acquisition system 490. The gain of theA/D converter 490 is controlled by the microprocessor 460 by signalsalong control line 492 in order to match the signal amplitude and/or theresolution to a range appropriate for the function of the A/D converter490. The data acquisition system 490 is configured to acquire EGMsignals, convert the raw analog data into a digital signal, and storethe digital signals for later processing and/or telemetric transmissionto an external device 230. The data acquisition system 490 is coupled tothe EGM electrode 402 through switch bank 74 to sample cardiac signals.The microcontroller 460 is further coupled to a memory 494 by a suitabledata/address bus 496, wherein the programmable operating parameters usedby the microcontroller 460 are stored and modified, as required, inorder to customize the operation of monitoring device 400 to suit theneeds of a particular patient. Such operating parameters define, forexample, the particular parameters to be used to detect stroke or AF.

EGM-based heart activity detector unit 78 detects cardiac rhythm,including heart rate and heart variability, and cardiac morphology. Thedisclosure utilizes the sense amplifier 482 to sense electrical signalsto determine whether a cardiac rhythm is physiologic or pathologic. Asused herein, “sensing” Is reserved for the noting of an electricaldepolarization, and “detection” is the processing of sequential senseddepolarization signals potentially in conjunction with the sensor inputto establish a diagnosis of an arrhythmia. The timing intervals betweensensed events (e.g., P-P Intervals or R-R Intervals) are detected by atiming control unit 79 of microcontroller 460 and then classified by anEGM-based heart activity detector unit 78 by, for example, comparing theIntervals to predefined rate zone limits indicative of, e.g., atachycardla, bradycardia, AF, or asystole episode. Techniques fordetermining arrhythmias in an implantable device are described, forexample, in U.S. Pat. No. 9,295,852 (Williamson), which is incorporatedherein by reference. Techniques for measuring and quantifying HRV aredescribed, for example, in U.S. Patent Pub. No. 20110066055 (Bharmi etal.), incorporated herein by reference. HRV is a measure of thevariation in heart rate over time. Briefly, in one example describedtherein, HRV is assessed based on an analysis of R-R intervals,including various frequency components thereof.

Event detector unit 77 may use the output of heart activity detectorunit 78 and/or cardiac signals from an analog to digital (A/D) dataacquisition system 490 to detect events, such as myocardial Infarctions,cardiac ischemia, strokes, and pain. For example, HRV can be reduced byboth stroke and cardiac ischemia. However, reductions in HRV may be morepronounced from stroke than when cardiac ischemia occurs and hence HRVcan be used to discriminate stroke from cardiac ischemia, at leastwithin some patients. One possible reason for this difference is thatthe efferent neural pathways involved in heart rate control are affectedby stroke, but not necessarily from a site of cardiac ischemia. For adiscussion of the effects of stroke on HRV see, for example, Tokgozogluat al. “Effects of Stroke Localization on Cardiac Autonomic Balance andSudden Death” Stroke 1999, 30, 1307-1311, incorporated herein byreference.

U.S. Pat. No. 8,241,221 (Park), incorporated herein by reference in itsentirety, describes techniques that may be used in accordance with thepresent disclosure for detecting stroke within a patient using asubcutaneous monitor based on an analysis of features of an electrogram(EGM) sensed within the patient. Exemplary EGM features indicative ofpossible stroke include the onset of prominent U-waves, the onset ofnotched T-waves, and changes in ST segment duration or QT duration ordynamic trends in these parameters. ST segment variations may be causedby abnormalities in the polarizations of cardiac tissue during an acutemyocardial infraction. ST segment variations may arise because ofdifferences in the electric potential between cells that have becomeischemic and those cells that are still receiving normal blood flow. STsegment variations may be an indication of injury to cardiac muscle,changes in the synchronization of ventricular muscle depolarization,drug or electrolyte influences, or the like.

U.S. Pat. No. 8,469,897 (Toren-Herrinton, et al.), incorporated hereinby reference in its entirety, describes techniques that may be used inaccordance with the present disclosure for determining the onset anddetermination of an ischemic or AMI condition based on a ST segmentdeviation. The cardiac cycle is composed of a P-wave, a Q-wave, anR-wave, an S-wave, and a T-wave. The portion of the signal between theS-wave and T-wave constitutes a ST segment. The ST segment may have avoltage level that aligns with the voltage level of a baseline heartrhythm. Alternatively, the ST segment may have a voltage level that isshifted above or shifted below the baseline. ST segment variationsindicate a potential coronary episode. ST segment variations may includeST deviations or ST shifts. A ST deviation is determined by subtractingan average PQ segment (e.g., the isoelectric segment) voltage from theST segment voltage for a heartbeat. The ST deviation provides a measureof the change in variability over a period of time. A ST shift isdetermined by changes in the ST deviation over a period of time. Forexamples a current ST shift may be calculated by subtracting a storedbaseline ST deviation from a newly acquired ST deviation. ST deviationsand ST shifts may be calculated as averages over multiple cardiac cyclesas well.

The discrimination of ischemia related and non-ischemia related shiftsin the ST segment may be determined by the event detector 77 by using astatistical determination of the variability of the ST segment shift.For example, a plurality of ST segment shifts may be collected to obtaina ST threshold. Then the ST threshold is used in a comparison withsubsequently measured ST segment shifts to identify the onset of acoronary episode. When the measured ST segment shift is less than a STthreshold, the termination of the coronary episode may be identified.Upon detecting the onset of a coronary episode, either an ischemic eventor an AMI event, the cardiac signals are stored in memory 494.

One or more physiologic sensors 108 may be mounted on or withinmonitoring device 400 or otherwise in communication with monitoringdevice 400. Event detector unit 77 may base the detection of events onthe output of one or physiologic sensors 108. Various physiologicsensors that can be used in conjunction with the current Invention arediscussed in: U.S. patent application Ser. No. 11/856,443, of Zhao,filed Sep. 17, 2007, entitled “MEMS-Based Left Atrial Pressure Sensorfor use with an Implantable Medical Device” and in U.S. patentapplication Ser. No. 11/623,663, filed Jan. 16, 2007, of Zou et al.,entitled “Sensor/Lead Systems for use with Implantable Medical Devices,”each of which is incorporated herein by reference in its entirety.Physiological sensors 108 may be one or more motion sensors,acceleration sensors such as an accelerometer, gyroscope, temperaturesensors, minute ventilation sensors, posture sensors, impedance sensors,optical sensors, oxygen saturation sensors, and the like. The followingpatents, each of which is incorporated herein by reference in itsentirety, describe exemplary activity sensors that may be used as aphysiologic sensor 108: U.S. Pat. No. 6,658,292 to Kroll at al.,entitled “Detection of Patient's Position and Activity Status using 3DAccelerometer-Based Position Sensor”; U.S. Pat. No. 6,625,493 (Kroll etal.), entitled “Orientation of Patient's Position Sensor using ExternalField”; U.S. Pat. No. 6,466,821 (Planca et al.), entitled “AC/DCMulti-Axis Accelerometer for Determining Patient Activity and BodyPosition;” U.S. Pub. No. 20150265839, entitled “Temperature Sensor for aLeadless Cardiac Pacemaker.” An impedance sensor may be used to measurealterations of impedance through the chest cavity to determine changesin breathing. Respiration sensors such as impedance sensors may be usedto monitor exertion and shortness of breath, which may be used by eventdetector unit 77 in conjunction with cardiac signals from A/D 490, as anindicator of a myocardial infraction. In certain embodiments, patientposture data is determined from sensed EGM data, as described in U.S.Pat. No. 7,636,599 (Koh et al.).

One or more Interaction sensors 109 (discussed in further detail below)may be mounted on or within monitoring device 400 or otherwise incommunication with monitoring device 400, in order to permit a user,such as the patient or a family member, to trigger a wirelesscommunication connection 250 between monitoring device 400 and anexternal device 230. In certain embodiments, interaction sensors 109 mayalso be used to trigger activation of EGM storage.

The operating parameters of implantable monitoring device 400 may benon-invasively programmed Into the memory 494 through telemetry circuit424 in telemetric communication with external device 230 or otherexternal device, such as a programmer, transtelephonic transceiver, or adiagnostic system analyzer. The telemetry circuit 424 is activated bythe microcontroller 460 by a control signal 406. The telemetry circuit424 advantageously allows SubQ EGM electrograms and status informationrelating to the operation of monitoring device 400 (as contained in themicrocontroller 460 or memory 494) to be sent to external device 230through an established communication link 250, and then on to acentralized processing system, where appropriate. The telemetry circuit424 also allows an Implantable monitoring device 400 to include apatient-triggered activation option for EGM storage. The telemetrycircuit 424 permits communication between monitoring device 400 andexternal physiologic sensor(s) 108 located in other location(s) and/orother devices (e.g., drug pumps or patient worn/carried electronicdevices or sensors).

The Implantable monitor additionally includes a battery 110 thatprovides operating power to all of the circuits shown in FIG. 4A. Thebattery is capable of operating at low current drains for long periodsof time for monitoring. The battery 110 also should have a predictabledischarge characteristic so that elective replacement time can bedetected.

In accordance with various embodiments disclosed below, themicrocontroller 460 may also include a wireless communication controlmodule 220, which may operate as the wireless communication controlmodule 220 of FIG. 1.

Moreover, the wireless communication control module 220 may include anannouncement timing control module 222 serving as the announcementtiming control module 222 of FIG. 1. In such examples, the telemetrycircuit 424 may be operated as the wireless communication interface 210of FIG. 1, such as a Bluetooth® interface or another wirelesscommunication interface implementing some wireless communicationprotocol or standard. In some embodiments, the announcement timingcontrol module 222 may receive information from the subcutaneous sensingcircuit 482, the data acquisition system 490 (e.g., when an arrhythmiaoccurs), and/or the like, as well as other information available withinthe monitoring device 400, either directly or via stored data in thememory 494, to determine a desired announcement frequency.

In addition to or in conjunction with increasing frequency ofannouncements, monitoring device 400 may also issue a patient alert whenan event or potential event, such as acute myocardial Infarction orstroke, is detected. The patient alert may direct external device 230 tocall an emergency number, such as 911. The alert may also instruct thepatient and/or caregiver to move within the external device's 230connection range. The alert may also prompt the external device 230 toprovide instructions to the user to, e.g., call 911 or their healthcareprovider and/or provide a questionnaire (e.g., through an app) toconfirm a detected event.

The microcontroller 460, in one embodiment, may perform the functions ofthe heart activity detector 78, event detector 77, the timing control79, the wireless communication control module 220, and/or otherfunctions described herein by executing instructions stored in thememory 494. Accordingly, the microcontroller 460 may operate as theheart activity detector 78 for periods of time, the event detector 77for periods of time, the timing control 79 for other periods of time,and so on. In some examples, the microcontroller 460 may operate asthese particular functional blocks in a concurrent or parallel manner.

In certain embodiments, an electronic device 200, e.g., monitoringdevice 400 (FIG. 4A) or Implantable stimulation device 100 (FIG. 4B),may include a neuromodulation implantable pulse generator (IPG) and aneuro stimulation pulse generator circuit to generate stimulation pulsesfor a brain or spinal cord nervous system, such as those used for spinalcord stimulation (SCS) or deep brain stimulation (DBS). The stimulationpulses may be delivered by a plurality of electrodes through a neurooutput lead. The neuro stimulation pulse generator circuit may becontrolled by a microcontroller via appropriate control signals totrigger or generate the stimulation pulses. Examples of EPGs that may beused with the current invention are disclosed in U.S. Pat. No. 9,288,614and U.S. Pat. No. 8,983,604 (Keel et al.), each of which is incorporatedherein by reference in its entirety. For example, Keel et al. describe aneurostimulation system, which may be an SCS system, having a lead withvarious electrodes for implant within an epidural space of an upperthoracic region of the patient. The SCS device is equipped to sense bothneural electrical signals and far-field cardiac electrical signals andto discriminate therebetween. In one specific example, the SCS devicehas a cardiac sense amplifier and a separate neural sense amplifier. Inan example where a single wideband sense amplifier is instead provided,the SCS device selectively filters a frequency spectrum sensed by thewide-band amplifier to separate cardiac signals from neural signals.Still further, the SCS device may identify and distinguish variouscardiac events such as atrial depolarization events (P-waves);ventricular depolarization events (R-waves); and ventricularrepolarization events (T-waves) using one or more sensing vectors, i.e.a particular combination of electrodes with which signals are sensed.Different cardiac events can be distinguished based, for example, onsignal amplitude, signal slope, signal morphology, sensing vector orsensing electrode spacing. For example, a vector spanning the atria ofthe heart will more readily sense P-waves; whereas a vector remote fromthe atria will typically not sense P-waves and so a comparison offar-field signals derived from those different vectors may be used todiscriminate P-waves from R-waves. The relative spacing of electrodepairs can also provide a basis for distinguishing R-waves from P-waves,with relatively wider Inter-electrode spacing providing signals thatemphasize R-waves as opposed to P-waves. That is, the device may beequipped to record or obtain cardiac signals from a different electrodeconfiguration (i.e. “vector”) than used for the neural sensing electrodeconfiguration to help distinguish cardiac signals from neural signals.For example, for an Octrode™ lead, the distal electrode to “Can” is arelatively large field vector that picks up the R-wave; whereas thedistal to “Ring 8” is a narrower field vector that picks up atrialactivity. An Octrode™ lead is a type of linear eight electrodepercutaneous lead provided by St Jude Medical™.

An electronic device 200, including monitoring device 400 andimplantable stimulation device 100 and may uses P-waves, R-waves andother features of the cardiac signal to detect heart rate variability(HRV), atrial and ventricular arrhythmias, prolonged QT intervals, STsegment shifts or deviations, ischemia or other cardiac conditions orparameters. Insofar as HRV is concerned, the device may detect: highfrequency (HF) components of HRV; low frequency (LF) components of HRV;and very low frequency (VLF) components of HRV, as well as a pNN50statistical value.

The electronic device 200 device may detect myocardial infarctions basedon shifts or deviations in ST segments. An elevation of ST segments maybe used as an indicator of potentially life-threatening acute myocardialInfarction requiring immediate intervention. An ST segment depressionmay be used as an indicator that the patient has partially occludedarteries, requiring monitoring and possibly therapeutic interventions,such as medication. The electronic device 200 may detect pain based on acombination of elevated heart rate and patient movement associated withpain.

FIG. 4B illustrates a simplified block diagram of the multi-chamberimplantable cardiac stimulation device 100, which may be capable oftreating both fast arrhythmia and slow arrhythmia with stimulationtherapy, including cardioversion, defibrillation, and pacingstimulation. The particular multi-chamber device 100 shown in FIG. 4B isfor illustration purposes only, and one of ordinary skill in thepertinent art could readily duplicate, eliminate, or disable theappropriate circuitry in any desired combination to provide a devicecapable of treating the appropriate one or more chambers withcardioversion, defibrillation, and/or pacing stimulation.

The stimulation device 100 may include a housing 40 which is oftenreferred to as a “can,” “case,” or “case electrode,” and which may beprogrammably selected to act as the return electrode for all “unipolar”modes. The housing 40 may further be used as a return electrode alone orin combination with one or more of the coil electrodes 28, 36, or 38(FIG. 3B), for defibrillation shocking purposes. The housing 40 mayfurther include a connector having a plurality of terminals 42, 43, 44,45, 46, 48, 52, 54, 56, and 58 (shown schematically and, forconvenience, the names of the electrodes to which they are connected areshown next to corresponding terminals). As such, in order to achieveright atrial sensing and stimulation, the connector may include at leastone right atrial tip terminal (A_(R) TIP) 42 adapted for connection tothe atrial tip electrode 22. The connector may also Include a rightatrial ring terminal (A_(R) RING) 43 for connection to the right atrialring electrode.

To achieve left chamber sensing, pacing, and/or shocking, such aconnector may include a left ventricular tip terminal (V_(L) TIP) 44, aleft ventricular ring terminal (V_(L) RING) 45, a left atrial ringterminal (A_(L) RING) 46, and a left atrial shocking coil terminal(A_(L) COIL) 48, that are adapted for connection to the left ventriculartip electrode 26, a left ventricular ring electrode (not shown), theleft atrial ring electrode 27, and the left atrial coil electrode 28,respectively (FIG. 3B).

To support right ventricular sensing, pacing, and/or shocking, theconnector may further include a right ventricular tip terminal (V_(R)TIP) 52, a right ventricular ring terminal (V_(R) RING) 54, a rightventricular shocking coil terminal (R_(V) COIL) 56, and an SVC shockingcoil terminal (SVC COIL) 58, which are adapted for connection to theright ventricular (RV) tip electrode 32, the RV ring electrode 34, theRV coil electrode 36, and the SVC coil electrode 38, respectively.

At the core of the stimulation device 100 is a programmablemicrocontroller 60 that may control the various modes of stimulationtherapy. The microcontroller 60 may include a microprocessor orequivalent control circuitry designed specifically for controlling thedelivery of stimulation therapy, and may include random access memory(RAM) and/or read-only memory (ROM), logic and timing circuitry, statemachine circuitry, and/or input/output (I/O) circuitry. Further, themicrocontroller 60 may have the ability to process or monitor variousInput signals (data) as controlled by a program code stored in adesignated block of memory. Exemplary types of control circuitry thatmay be used with the invention include the microprocessor-based controlsystem of U.S. Pat. No. 4,940,052 (Mann et. al.) and the state-machinesof U.S. Pat. No. 4,712,555 (Thomander et al.) and U.S. Pat. No.4,944,298 (Sholder), each of which is incorporated herein by referencein its entirety.

In the embodiment of FIG. 4B, the stimulation device 100 includes anatrial pulse generator 70 and a ventricular pulse generator 72 that maygenerate stimulation pulses for delivery by the right atrial lead 20,the right ventricular lead 30, and/or the coronary sinus lead 24 via anelectrically configurable switch 74. To provide the stimulation therapyin each of the four chambers of the heart 12, the atrial pulse generator70 and the ventricular pulse generator 72 may include, for example,dedicated pulse generators, independent pulse generators, multiplexedpulse generators, and/or shared pulse generators. The atrial pulsegenerator 70 and the ventricular pulse generator 72 may be generallycontrolled by the microcontroller 60 via appropriate control signals 76and 98, respectively, to trigger or inhibit the stimulation pulses.

The microcontroller 60 may further include timing control circuitry 79,which may be used to control timing of the stimulation pulses such as,for example, pacing rate, atrio-ventricular (AV) delay, atrialinterchamber (A-A) delay, and/or ventricular Interchamber (V-V) delay.Such timing control circuitry 79 may also be used to keep track of thetiming of refractory periods, noise detection windows, evoked responsewindows, alert intervals, marker channel timing, and so on.

The switch 74 may include a plurality of switches for connecting thedesired electrodes to the appropriate I/O circuits, thereby providingcomplete electrode programmability. Accordingly, the switch 74, inresponse to a control signal 80 from the microcontroller 60, maydetermine the polarity of the stimulation pulses (e.g., unipolar,bipolar, cross-chamber, and the like) by selectively opening and closingthe appropriate combination of switches. Atrial sensing circuits 82 andventricular sensing circuits 84 may also be selectively coupled to theright atrial lead 20, coronary sinus lead 24, and the right ventricularlead 30 through the switch 74 for detecting the presence of cardiacactivity in each of the four chambers of the heart 12.

Accordingly, the atrial sensing circuit 82 and the ventricular sensingcircuit 84 may include dedicated sense amplifiers, multiplexedamplifiers, and/or shared amplifiers. The switch 74 determines the“sensing polarity” of the cardiac signal by selectively closing theappropriate switches of the switch 74. In this way, the clinician mayprogram the sensing polarity independent of the stimulation polarity.

Each of the atrial and ventricular sensing circuits 82, 84 may employone or more low-power precision amplifiers with programmable gain,automatic gain, and/or sensitivity control, one or more band-passfilters, and/or a threshold detection circuit, to selectively sense thecardiac signal of interest. The automatic sensitivity control may enablethe stimulation device 100 to deal effectively with the difficultproblem of sensing the low amplitude signal characteristics of atrial orventricular fibrillation.

The outputs of the atrial sensing circuit 82 and ventricular sensingcircuits 84 may be connected to the microcontroller 60 for triggering orinhibiting the atrial and ventricular pulse generators 70 and 72,respectively, in a demand fashion in response to the absence or presenceof cardiac activity, respectively, in the appropriate chambers of theheart 12. The atrial and ventricular sensing circuits 82 and 84, inturn, may receive control signals over signal lines 86 and 88 from themicrocontroller 60 for controlling the gain, threshold, polarizationcharge removal circuitry, and the timing of any blocking circuitrycoupled to the inputs of the atrial and ventricular sensing circuits 82and 84.

For arrhythmia detection, the stimulation device 100 may include a heartactivity detector 78 that utilizes the atrial and ventricular sensingcircuits 82 and 84 to sense cardiac signals for determining whether arhythm may be physiologic or pathologic. As used herein, “sensing”generally refers to the process of noting an electrical signal, while“detection” generally refers to the step of confirming the sensedelectrical signal as the signal being sought by the detector. As anexample, “detection” applies to the detection of both proper rhythms(i.e., “P wave” or “R wave”) as well as improper dysrhythmias includingarrhythmia and bradycardia (e.g., detection of the absence of a properrhythm).

The timing intervals between sensed events (e.g., P-waves, R-waves,and/or depolarization signals associated with fibrillation which aresometimes referred to as “F-waves” or “Fib-waves”) may then beclassified by the heart activity detector 78 by comparing them to apredefined rate zone limit (e.g., bradycardia, normal, low-rateventricular tachycardia, high-rate ventricular tachycardia, fibrillationrate zones, and so on) and various other characteristics (e.g., suddenonset, stability, morphology, information from one or more physiologicsensors 108, and so on) to determine the type of remedial therapyrequired (e.g., bradycardia pacing, anti-tachycardia stimulation,cardioversion shocks, and/or defibrillation shocks, collectivelyreferred to as “tiered therapy”).

Physiologic sensors 108 may be mounted on a lead or mounted on or withinstimulation device 100 or otherwise In communication with stimulationdevice 100. Various physiologic sensors that can be used in conjunctionwith the current invention are discussed in: U.S. patent applicationSer. No. 11/856,443, of Zhao, filed Sep. 17, 2007, entitled “MEMS-BasedLeft Atrial Pressure Sensor for use with an Implantable Medical Device”and In U.S. patent application Ser. No. 11/623,663, filed Jan. 16, 2007,of Zou et al., entitled “Sensor/Lead Systems for use with ImplantableMedical Devices,” each of which is incorporated herein by reference inits entirety. Physiological sensors 108 may be one or more motionsensors, accelerometers, gyroscopes, temperature sensors, minuteventilation sensors, posture sensors, impedance sensors, opticalsensors, oxygen saturation sensors, and the like. The following patents,each of which is incorporated herein by reference In its entirety,describe exemplary activity sensors that can be used to determinepatient activity: U.S. Pat. No. 6,658,292 to Kroll et al., entitled“Detection of Patient's Position and Activity Status using 3DAccelerometer-Based Position Sensor”; U.S. Pat. No. 6,625,493 to Krollet al., entitled “Orientation of Patient's Position Sensor usingExternal Field”; U.S. Pat. No. 6,466,821 to Pianca et al., entitled“AC/DC Multi-Axis Accelerometer for Determining Patient Activity andBody Position;” U.S. Pub. No. 20150265839, entitled “Temperature Sensorfor a Leadless Cardiac Pacemaker.” An impedance sensor may be used tomeasure alterations of impedance through the chest cavity to determinechanges in breathing. Respiration sensors such as impedance sensors maybe used to monitor exertion and shortness of breath, which may beindicative of a myocardial Infraction.

One or more interaction sensors 109 (discussed in further detail below)may be mounted on or within stimulation device 100 or otherwise incommunication with stimulation device 100, in order to permit a user,such as the patient or a family member, to trigger a wirelesscommunication connection 250 between stimulation device 100 and anexternal device 230. In certain embodiments, interaction sensors 109 mayalso be used to trigger activation of EGM storage.

Cardiac signals and other sensed signals may also be applied to theinputs of a data acquisition system 90 which is depicted as ananalog-to-digital converter (ADC) for simplicity of illustration. EGMsignals and other sensed signals are also applied to the inputs of ananalog to digital (A/D) data acquisition system 490. The gain of the ADCconverter 90 is controlled by the microprocessor 60 by signals alongcontrol line 92 in order to match the signal amplitude and/or theresolution to a range appropriate for the function of the ADC converter90. The data acquisition system 90 may be configured to acquireintracardiac electrogram (EGM) signals, convert the raw analog data Intodigital signals, and store the digital signals for later processingand/or telemetric transmission (e.g., via wireless signals 250) to anexternal device 230 by way of telemetry circuit 424. Such a dataacquisition system 90 may be coupled to the right atrial lead 20, thecoronary sinus lead 24, and/or the right ventricular lead 30 through theswitch 74 to sample the cardiac signals across any pair of desiredelectrodes.

The microcontroller 60 may further be coupled to a memory 94 by asuitable data/address bus 96, wherein the programmable operatingparameters used by the microcontroller 60 may be stored and modified, asrequired, so as to customize the operation of the stimulation device 100to suit the needs of particular patients. Such operating parameters maydefine, for example, stimulation pulse amplitude, pulse duration,polarity of electrodes, rate, sensitivity, automatic features,arrhythmia detection criteria, and/or the amplitude, shape of waves,and/or vector of each stimulation pulse to be delivered to the patient'sheart 12 within each respective tier of therapy. The telemetry circuit424 is activated by the microcontroller 60 by a control signal 106.

The operating parameters of implantable stimulation device 100 may benon-invasively programmed into the memory 94 through telemetry circuit424 in telemetric communication with external device 230 or otherexternal device, such as a programmer, transtelephonic transceiver, or adiagnostic system analyzer. The telemetry circuit 424 is activated bythe microcontroller 60 by a control signal 106. The telemetry circuit424 advantageously allows electrograms and status information relatingto the operation of stimulation device 100 (as contained in themicrocontroller 60 or memory 94) to be sent to external device 230through an established communication link 250, and then on to acentralized processing system, where appropriate. The telemetry circuit424 also allows a stimulation device 100 to include a patient-triggeredactivation option for electrogram storage. The telemetry circuit 424permits communication between stimulation device 100 and externalphysiologic sensor(s) 108 located in other location(s) and/or otherdevices (e.g., drug pumps or patient wom/carried electronic devices orsensors).

The stimulation device 100 may additionally include a power source thatmay be Illustrated as a battery 110 for providing operating power to allthe circuits of FIG. 4B. For the stimulation device 100 employingshocking therapy, the battery 110 may be capable of operating at lowcurrent drains for long periods of time, such as, for example, less than10 microamps (μA), and may also be capable of providing high-currentpulses using shocking circuit 116 controlled by the microcontroller 60via control signals 118 when the patient requires a shock pulse (e.g.,in excess of 2 A at voltages above 2 volts (V) for periods of 10 seconds(s) or more).

In accordance with various embodiments disclosed below, themicrocontroller 60 may also include a wireless communication controlmodule 220, which may operate as the wireless communication controlmodule 220 of FIG. 1.

Moreover, the wireless communication control module 220 may Include anannouncement timing control module 222 serving as the announcementtiming control module 222 of FIG. 1. In such examples, the telemetrycircuit 424 may be operated as the wireless communication Interface 210of FIG. 1, such as a Bluetooth® interface or another wirelesscommunication interface implementing some wireless communicationprotocol or standard. In some embodiments, the announcement timingcontrol module 222 may receive information from the atrial andventricular sensing circuits 82, 84, the data acquisition system 90(e.g., when an arrhythmia occurs), and/or the like, as well as otherinformation available within the implantable stimulation device 100,either directly or via stored data in the memory 94, to determine adesired announcement frequency.

The microcontroller 60, in one embodiment, may perform the functions ofthe event detector 77, the timing control 79, the wireless communicationcontrol module 220, and/or other functions described herein by executinginstructions stored in the memory 94. Accordingly, the microcontroller60 may operate as the event detector 77 for periods of time, the timingcontrol 79 for other periods of time, and so on. In some examples, themicrocontroller 60 may operate as these particular functional blocks ina concurrent or parallel manner.

Additional and alternative details of implantable stimulation device 100can be found in U.S. Pat. No. 5,405,363 (Kroll et al.) and U.S. Pat. No.5,040,534 (Mann et al.), each of which are incorporated herein byreference in its entirety.

Event detector 77 may detect a preliminary Indication of stroke based onan analysis of the output of heart activity detector 78, e.g., T-waves,U-waves (if present), ST segments, and QT segments, as described in U.S.Pat. No. 8,241,211 (Park), incorporated herein by reference.

U.S. Pat. No. 8,989,852 (Gill, et al.), incorporated herein by referencein its entirety, describes techniques that may be used in accordancewith the present disclosure for detecting and distinguishing stroke andcardiac ischemia based on electrocardiac signals. In one example, thedevice senses atrial and ventricular signals within the patient along aset of unipolar sensing vectors and identifies certain morphologicalfeatures within the signals such as PR intervals, ST intervals, QTintervals, T-waves, etc. The device detects changes, if any, within themorphological features such as significant shifts in ST intervalelevation or an Inversion in T-wave shape, which are indicative ofstroke or cardiac ischemia. By selectively comparing changes detectedalong different unipolar sensing vectors, the device distinguishes ordiscriminates stroke from cardiac ischemia within the patient. Thediscrimination may be corroborated using various physiological andhemodynamic parameters.

FIG. 5 is a list of example announcement frequency factors 500 that mayinfluence operation of the announcement timing control module 222 ofFIGS. 1, 4A and 4B. Examples of the announcement frequency factors 500may include, but are not limited to, a current time of day 502, acurrent detected heart activity 504 (e.g., heart rate, HRV or HRT,morphology, sinus rhythm, tachycardia, bradycardia, atrial fibrillation,ventricular fibrillation, asystole), a heart activity history 506, acurrent detected patient body position and/or physical activity level508, a patient body position and/or physical activity level history 510,a current detected event 512 (e.g., myocardial Infarction, stroke,cardiac ischemia, angina, neuropathic pain), a diagnostics history 514(detected by an electronic device 200 or and/or programmed by a user), acurrent detected interaction status 516, a current wirelesscommunication connection status 518, and a current battery charge level520. Other factors 500 not listed in FIG. 5 (e.g., body temperature) maybe employed, and some factors 500 depicted in FIG. 5 may not be employedwhen determining an appropriate announcement frequency.

The announcement timing control module 222 advantageously minimizesover-advertising by the electronic device 200 during periods whenexternal device 230 is unlikely trying to connect, while improving theuser experience during the connection process by increasingadvertising/announcement frequency at times when a user is likely toinitiate such a connection. In addition, announcement timing controlmodule 222 advantageously increases connection speed between theelectronic device 200 and external device 230 during critical periods,such as when the patient is experiencing an acute myocardial Infarctionor stroke, in order to enhance patient safety and clinical outcome.

In an embodiment, the announcement timing control module 222 may basethe announcement frequency at least in part on the current time of day502. In one example, the electronic device 200 may include a real-timeclock from which the current time of day 502 may be determined. In oneexample, a lower frequency may be used during times when the patient inwhich the electronic device 200 is implanted is expected to be asleep,such as approximately 10 PM to 6 AM, while a higher frequency may beutilized during times when the patient is expected to be awake. Anexpected time of sleep (e.g., 10 PM to 6 AM) and an expected time ofwakefulness (e.g., 6:01 AM to 9:59 PM) may be programmed parametersentered by a user using an external device 230 and telemetry circuit 424of electronic device 200. An expected time of sleep and an expected timeof wakefulness may also be “learned” or modified by the electronicdevice 200, as discussed in more detail below. The particular times ofday and their associated announcement frequencies may be configured byway of the telemetry circuit 424, or via other means. Also, the time ofday 502 may be synchronized with the local time zone based oninformation received at the electronic device 200, such as informationreceived via the wireless communication interface 201, such as telemetrycircuit 424.

In certain embodiments, the announcement timing control module 222 mayuse current detected body position and/or physical activity level 508,such as posture, to confirm or corroborate a determination ofannouncement frequency based on current time of day. For example, aphysiological sensor 108, such as an acceleration sensor, e.g., anaccelerometer, may detect a patient's posture based on the accelerationof electronic device 200. If the patient is lying down, this maycorroborate that a lower frequency may be used based on a current timeof day 502 when the patient in which the electronic device 200 isimplanted is expected to be asleep. If the patient is, however, notlying down based on, e.g., the accelerometer's reading, the announcementtiming control module 222 may determine that a higher frequency ofannouncement should be used regardless of the current time of day 502.In this way posture, and/or other activity level data, may be used inconjunction with time of day in order to decrease the frequency ofannouncements at times when the patient is likely to be asleep, and thusunlikely to attempt communication with an external device.

In certain embodiments, the announcement timing control module 222determines an expected time of sleep and an expected time of wakefulnessby monitoring a patient over a baseline period of time, e.g., weeks ormonths, using physiological sensors 108 to log physical activity datawith time of day into memory.

In certain embodiments, the announcement timing control module 222 keepsa log of the time of day 502 at which a user attempts to initiate aconnection between the electronic device 200 and external device 230.Announcement timing control module 222 may use the log to determinetrend information regarding the time of day that a user typicallyattempts to initiate such a connection. The announcement frequency maythen be adjusted based on the trend data.

In some implementations, the announcement timing control module 222 maybase the announcement frequency at least in part on the current detectedheart activity 504 and/or the heart activity history 506. Theannouncement frequency control module 222 may interpret heart activity504 such as a heart rate exceeding some threshold, tachycardia, HRV orHRT less than a threshold, certain morphologies, ST segment shifts lessthan a ST shift threshold, atrial fibrillation, ventricularfibrillation, and asystole, as conditions warranting increasing theannouncement frequency to support faster creation of a wirelesscommunication connection between the implantable stimulation device 100and/or monitoring device 400 and the external device 230. In someexamples, an abnormally low heart rate, such as one that falls belowsome threshold (e.g., indicative of Bradycardia, Sick Sinus Syndrome orprofound long pauses), may also be considered pathological and/orunstable, prompting the announcement frequency control module 222 toincrease the announcement frequency for at least some period of timeafter initial detection. Oppositely, a relatively normal or stable heartrate may influence the announcement frequency control module 222 tolower the current announcement frequency such as to conserve theelectronic device's battery.

In certain embodiments, the announcement frequency may be dependent onduration of the detected heart activity 504. Announcement frequency maynot be altered until the detected heart activity 504 has a durationlonger than a threshold and announcement frequency may be increased inincrements (in some embodiments, up to a limit) dependent on theduration of the detected heart activity 504 being longer thanincrementally longer thresholds. For example, an AF lasting less than 5minutes may not trigger an increase in announcement frequency. An AFlasting one hour or more may trigger a higher announcement frequencythan an AF lasting between 5 minutes and an hour. In certainembodiments, an AF lasting more than an hour will not trigger anyfurther increase in announcement frequency, unless other factors (eitherdetected or programmed) are present.

In certain embodiments, electronic device 200 may tier the seriousnessof the detected heart activity 504 and provide different announcementfrequencies depending on the relative seriousness, e.g., the mode ofadvertising for a VF may be very faster (e.g., every 1-10 seconds) thanan VT (e.g., every 20-30 seconds) and the mode of advertising for a VTmay be faster than an AF (e.g., every 30-40 seconds). The ranking mayalso be dependent on other factors, such as those detected byphysiological sensor 108 that may herald an acute episode or thepatient's diagnostic history 514 (which may either be detected by theelectronic device 200 or programmed by a user, e.g. prior stroke,myocardial infarction, ischemia, age CHADS2 score, etc.).

In some examples, the electronic device 200 (e.g., monitoring device 400(FIG. 4A) and/or implantable stimulation device 100 (FIG. 4B)) may storepreviously sensed heart activities, such as heart rates, heartbeatwaveforms, arrhythmias, and the like as heart activity history 506 inmemory 494 (FIG. 4A) or 94 (FIG. 4B), and use this data to “learn” orpredict times during the day when there is a higher probability of anabnormal heart activity to occur. The electronic device 200 may thenincrease the announcement frequency to support faster creation of awireless communication connection between the electronic device 200 andthe external device 230 during the periods when there is a higher chanceof an abnormal heart activity so that the patient activator (externaldevice 230) can be used immediately. Conversely, the electronic device200 may decrease the announcement frequency to support slower creationof a wireless communication connection between the electronic device 200and the external device 230 when there is a lower probability of anabnormal heart activity, e.g., to preserve battery function.

In some implementations, the announcement timing control module 222 maybase the announcement frequency at least in part on the current detectedpatient physical activity level 508 and/or the patient physical activitylevel history 510. The patient physical activity level 508 (which mayinclude positional data, e.g., prone or standing, blood pressure, andphysical exertion data) may be determined by one or more factors sensedvia one or more physiological sensors 108, which may be a motion sensor,accelerometer, gyroscope, temperature sensor, minute ventilation sensor,posture sensor, impedance sensors, optical sensors, oxygen saturationsensors, and the like. The possible presence of exercise-inducedarrhythmia and/or other signs of relatively strenuous patient physicalactivity (e.g., fast walking, jogging, etc.), as indicated via thecurrent detected patient physical activity level 508, may cause theannouncement frequency control module 222 to Increase the announcementfrequency to support faster creation of a wireless communicationconnection between the electronic device 200 and the external device230. More moderate Indications of activity (e.g., slow walking) may leadthe announcement control module 222 to determine that the announcementfrequency should be relatively slow or moderate to conserve electricalpower. Moreover, even lower levels of patient physical activity history(e.g., resting, reclining, sleeping for extended periods of time, and soon) may influence the announcement timing control module 222 to turn offannouncements altogether for the time being. (For methods of detectingrest and sleep states using an activity sensor that may be used inaccordance with the present disclosure, see U.S. Pat. No. 5,476,483,entitled “System and method for modulating the base rate during sleepfor a rate-responsive cardiac pacemaker” (Bornzin et al.) which ishereby incorporated herein by reference.) Ceasing announcements undersuch circumstances may be seen as an automatic implementation of an“airplane mode” often provided in other wireless communicationequipment.

In some embodiments, the electronic device 200 may store previouslydetected patient physical activity level history 510, against which thecurrent detected patient physical activity level 508 data may becompared to ascertain whether the current patient physical activitylevel 508 is relatively high or low for the patient, thus providing someindication to the announcement timing control module 222 as to whetherthe current announcement frequency should be maintained or altered.

In another example, the announcement timing control module 222 may basethe announcement frequency at least in part on a current detected event512 and/or the diagnostics history 514. The current detected event 512may be determined by one or more factors sensed via the subcutaneoussensing circuits 482, the atrial sensing circuits 82, the ventricularsensing circuits 84, one or more physiologic sensors 108, and/or fromthe output of the heart activity detector 78. Upon detection of alife-threatening event, such as an acute myocardial infarction or astroke, the electronic device 200 increases the announcement frequencyvia the announcement timing control module 222 in response to such anepisode.

In some examples, the external device 230 of FIGS. 1, 3A, 4A, and 4B maybe a device that may be manually activated by the patient when thepatient believes or feels that a heart-related clinical episode orpain-related episode has occurred. An indication of that activation maythen be transmitted via a wireless communication connection 250 betweenthe external device 230 and the electronic device 200. In some cases,the creation of a wireless communication connection 250 between theexternal device 230 and the electronic device 200 may be delayed due tothe lack of an announcement message from the electronic device 200, suchas due to a low announcement message frequency. Such a delay may thuscause an associated delay in the indication of patient activation beingreceived at the electronic device 200. However, if the announcementtiming control module 222 dynamically increases the announcementfrequency in response to detecting the same clinical episode, generationof the wireless communication connection 250 may occur more quickly,thus reducing the delay in receiving the patient indication from theexternal device 230, thereby rendering the indication as a moreeffective patient confirmation of the clinical episode.

Additionally, the announcement timing control module 222 may access thediagnostics history 514 maintained by the monitoring device 400 and/orimplantable stimulation device 100 to anticipate when next to advertisemore frequently. The announcement timing control module 222 may comparethe current heart activity status with previous detected heart clinicalconditions to verify and/or accelerate announcement frequency. Theannouncement timing control module 222 may also store time of day 502when a pathological heart activity is detected as part of thediagnostics history 514 in order to determine a trend in the data thatmay be used by announcement timing control module 222 to modulateadvertisement frequency based on time of day.

In another example, the announcement timing control module 222 may basethe announcement frequency at least in part on the current detectedinteraction status 516 of the electronic device 200. In one example, theelectronic device 200 may include an interaction sensor 109 (FIGS. 4Aand 4B), such as an accelerometer, that measures instantaneousacceleration of electronic device 200. In some embodiments, theannouncement timing control module 222 may interpret high accelerationsof short duration as a physical attempt by the patient or another person(e.g., a physical “tap” of the body near the electronic device 200) toincrease the announcement frequency. In some examples, an increase inthe announcement frequency may be initiated only upon the receipt of apredetermined sequence of taps detected via the Interaction sensor 109over some period of time. In other embodiments, the announcementfrequency may be decreased by a different tap sequence.

In yet other examples, the physical tapping interaction between thepatient or other person and the electronic device 200 may be detectedusing other sensors or transducers. For example, Interaction sensor 109may include an impedance monitor that may measure a voltage response toan induced current to determine if the impedance of a particular portionof the patient skin has been altered due to contact of the patients handwith an area near the electronic device 200.

In yet another example, interaction sensor 109 may include an audiomicrophone or other sensor may be employed within the electronic device200 to detect audible patient taps near the device 200. In yet anotherexample, the announcement frequency may change based on the physicalchange of body position, such as from supine to upright.

In yet another embodiment, Interaction sensor 109 may include a PPGsensor. For example, the Implantable stimulation device 100 mayincorporate one or more light sources, such as light-emitting diodes(LEDs) that emit light to a photo-detector. In this example, a change inthe amount of light from the LEDs detected at the photo-detector may beInterpreted as a patient tap of an area close to the device 100. Arhythmic tap will create a fluid shift that causes a rapid change in theoptical absorption of the local tissue that is unlikely to occur for anyreason other than patient initiation of the device.

In yet another embodiment, interaction sensor 109 may include one ormore magnets employed to detect interaction between the patient and theimplantable stimulation device 100.

The announcement timing control module 222 may base the announcementfrequency at least in part on the current connection status 518 of theimplantable stimulation device 100 in at least some embodiments. Forexample, if the current connection status 518 indicates that a wirelesscommunication connection 250 is currently coupling the implantablestimulation device 100 with the external device 230, the announcementtiming control module 222 may reduce the announcement frequency, or setthe frequency to zero, at least while the wireless communicationconnection is active. In some embodiments, the announcement timingcontrol module 222 may increase the announcement frequency for somedeterminable period of time following a disconnection of a wirelesscommunication connection 250 to facilitate reconnection.

In addition, the announcement timing control module 222 may base theannouncement frequency at least in part on the current charge level 520of the battery 110 of the monitoring device 400 or implantablestimulation device 100 in some implementations. For example, relativelyor extremely low charge levels of the battery 110 may cause theannouncement timing control module 222 to reduce the frequency of theannouncement messages, possibly to zero, for at least some period oftime to conserve battery charge.

According to some embodiments, the announcement timing control module222 may take Into account a combination of the above factors 500 todetermine an appropriate announcement frequency. For example, based onany or all of the heart activity history 506, the patient physicalactivity level history 510, and/or the diagnostics history 514, theannouncement timing control module 222 may determine one or more timesduring the day that the patient is typically more active, as well astimes during the day that the patient is more likely to experience aclinical episode, and increase the announcement frequency during atleast some of those times of day, as indicated by the current time ofday 502.

Various physiological parameters, hemodynamic parameters or cardiacrhythm parameters detected by the device can be used to confirm orcorroborate the determination of whether the condition is stroke orcardiac ischemia, and also to confirm or corroborate changes inannouncement frequency. For example, the heart rate can be monitored. Anincrease in heart rate is typically associated with stroke but notcardiac ischemia. As another example, heart rate variability (HRV) canbe monitored. Reductions in HRV may be more pronounced from stroke thanwhen cardiac ischemia occurs. Other parameters that can be monitoredinclude signals representative of one or more of: blood volume; bloodpressure; pre-ejection interval; heart rate turbulence (HRT), evokedresponse; capture threshold; kidney function; heart rate alternans,stroke volume and contractility. For example, a sudden increase in bloodpressure may be due to cardiac ischemia and hence would tend tocorroborate a diagnosis of ischemia. Pre-ejection intervals tend tobecome longer during cardiac ischemia but become shorter during stroke.Capture thresholds tend to increase due to cardiac ischemia, at least inthe vicinity of the ischemia. Alternans tends to occur in conjunctionwith cardiac ischemia but not stroke. A variety of these parameters canbe evaluated and then combined to yield a “score,” which is then used tocorroborate the determination of stroke vs. cardiac ischemla and maysimilarly be used by announcement timing control module 122 tocorroborate whether announcement frequency should be modified and atwhat frequency.

Different days of the week, such as Monday through Friday versusSaturday and Sunday, may be distinguished such that the announcementfrequency schedule may be different on weekdays versus weekends. Forexample, the heart activity level history 506, the patient physicalactivity level history 510, and/or the diagnostics history 514 mayindicate that on the weekend the patient (a “weekend warrior”) isexercising, which is Inducing tachyarrythmias, but on the weekdays thepatient is relatively sedentary, corresponding to periods of normalheart activity. Rather than treating all days equally and producing aweekly average based on time of day, the announcement timing controlmodule 222 may distinguish between days of the week that could benefitfrom more or less frequent communication.

In other examples, an indication of elevated heart activity level orpatient physical activity (e.g., by way of the current detected heartactivity 504 and/or the current detected patient physical activity level508), and/or an indication of an cardiac ischemia, myocardialinfarction, stroke, angina, or episode of pain (e.g., via the currentdetected event 512) may cause the announcement timing control module 222to increase the announcement frequency, even though the current time ofday 502 would otherwise dictate a relatively lower announcementfrequency. In some implementations, a physical tap by a patient, asindicated via the current detected interaction status 516, may alsocause an increase in the announcement frequency despite a current timeof day 502 indicating a lower frequency and a lack of any elevated heartor patient physical activity and an absence of any event, as describedabove (e.g. when the patient has vasovagal symptoms that are notassociated with abnormal cardiac rhythms). Thus, one or moreannouncement frequency factors 500 may override another one or more ofthe announcement frequency factors 500, thus implementing a hierarchyamong the factors 500.

In another specific example, one or more physiological sensors 108(shown in FIGS. 4A and 4B) acquires a current detected patient physicalactivity level 508 over a predetermined period of time (e.g., an hour,four hours, eight hours, a day and the like). For instance, anaccelerometer or an activity sensor may be used to sense body movementsof the patient. Alternatively, the activity sensor may be a workloadsensor or any other type of sensor that senses metabolic changes, suchas nutrition and oxygen consumption of the patient. Current detectedpatient physical activity level 508 data is analyzed to determinewhether a state of sustained exercise has been achieved. The state ofsustained exercise is declared when the level of activity is greaterthan a predetermined exercise threshold value (e.g., greater than 130%of at rest level) warranting modulation of announcement frequency.Alternatively, the sustained exercise state may be described when thecurrent detected patient physical activity level 508 is less than thepredetermined exercise threshold value, but the activity level remainsat an intermediate threshold level for a predetermined length of time(e.g., at 75% of the exercise threshold value for a sustained durationof five minutes, 20 minutes and the like). As a further alternative, thesustained exercise state may be declared when the activity levelincreases by a large incremental amount in a short period of time. Thecurrent detected patient physical activity level 508 may be stored inmemory 94 for later retrieval and processing and/or may be used byannouncement timing control unit 222 to trigger an increase inannouncement frequency.

Optionally, the current detected patient physical activity level 508 maybe compared to an activity level baseline value. The baseline of theactivity level data may be determined over a predetermined period oftime (e.g., one hour). The activity level data, to determine thebaseline, may be collected when the patient is minimally exertingherself. For example, a patient may be walking at a non-exercise pacefor the baseline predetermined period of time. The baseline may be anaverage of multiple values of a patient's activity over multiplepredetermined periods of time (e.g., one hour periods measured weekly).Alternatively, the baseline activity may be acquired only once in alonger period of time (e.g., once every six months) while the activitylevel data is acquired more often.

In an embodiment, as the patient exercises, current detected heartactivity 504 data, which includes, e.g., ST segments, arrhythmias, heartrate, etc. is acquired. The current detected heart activity 504 data iscollected over a series of cardiac cycles for a predetermined period oftime. For instance, the current detected heart activity 504 data may becollected over a ten minute or one hour sample interval. The currentdetected heart activity 504 data may be a series of intrinsicheartbeats. Alternatively, the current detected heart activity 504 datamay be a series of paced heartbeats, which are stimulated by either anatrial pulse generator or a ventricular pulse generator. Further, thecurrent detected heart activity 504 data may be collected before,concurrently with, or after the current detected patient physicalactivity level 508.

In an embodiment, an ST baseline may be determined based on the STsegment variations in the cardiac data. The ST baseline may bedetermined by collecting cardiac data when the patient is resting andnot moving (e.g., sitting or lying down). The baseline may be based ondata collected over a baseline predetermined period of time (e.g., anhour, four hours, a day and the like).

When detected patient physical activity level 508 is above a threshold,microcontroller 460 (FIG. 4A) or 60 (FIG. 4B) may monitor the cardiacdata (which may take more battery energy to detect) for, e.g., STsegment variations, such as ST shifts and ST deviations, as describedabove, and event detector 77 determines a current detected event 512,such as ischemic episodes (e.g., Ischemia, demand ischemia, acutemyocardial Infarction, stroke, an inconsistent physiology, and thelike). Depending on the seriousness of the ischemic episode detected byevent detector 77, the frequency of announcements may be increasedand/or the patient physical activity level that induced the ischemia maybe recorded in memory 94. Alternatively, a detected patient physicalactivity level that is a running average of activity level data from thetime of beginning exercise or from the time of the last ischemic episodemay be recorded. Further heart activity and patient physical activitylevel data may be recorded at the time of the ischemic episode, such as,heart rate, pacing rate, blood pressure, respiratory rate, oxygenconsumption, carbon-dioxide production, body motion, and the like thatmay corroborate the detected event and modulate announcement frequency.

For example, microcontroller 460 or 60 may determine whether the patientabruptly stopped exercising. For example, microcontroller 460 or 60monitors the physiologic sensor 108 (e.g., accelerometer) for anysignificant measurement drop over a predetermined window of time (e.g.,the measurement drop may be based on a percentage drop). For instance,the patient may have stopped exercising Immediately upon having theischemic episode because of anginal pain (e.g., a change in body postureimmediately following an ischemic episode). In the case where theelectronic device 200 is a neurostimulator, the patient may have stoppedexercising based upon neurogenic pain, and the device will record theseinstances as well in order to determine trends, as discussed in furtherdetail below. Alternatively, the patient may indicate an amount ofanginal pain (or neurogenic pain) by tapping their body proximate to theelectronic device 200 location. Microcontroller 460 or 60 may alsomonitor for a sudden increase in heart rate or other change in thepatient's movement characteristic of acute pain. If the patient stoppedexercising after the ischemic episode or there is a similar indication,the event detector 77 may detect pain and Increase advertisementfrequency in anticipation of the patient triggering connection of theexternal device with the electronic device.

Microcontroller 460 or 60 may also log whether or not the patientattempted such a connection even in the absence of device detectedanginal or neurogenic pain. Also, the external device (e.g., through anapp) may prompt the patient to enter the reason why the patienttriggered the device (e.g., angina pain, neurogenic pain, palpitations,syncope, etc.) and this information may be programmed into theelectronic device 200 and logged with the detected heart activity and/ordetected patient physical activity and stored in memory 494 (FIG. 4A) or94 (FIG. 4B). In this way, electronic device 200 records in memory(e.g., 94 or 494) that a detected heart activity and/or detected patientphysical activity level Is accompanied by an event, e.g., that an STshift is accompanied by anginal pain. Microcontroller 460 or 60 may alsolog the time of day 502 at which a detected heart activity and/ordetected patient physical activity level is accompanied by an event.However, if the patient did not stop exercising during an ischemicepisode and there is no other indication of an episode, such as angina,the electronic device 200 records in memory 94 or 494 that the heartactivity, e.g., ST shift, is not accompanied by anginal pain or otherepisode.

The microcontroler 60 and/or 460 may determine current detected patientphysical activity level 508 based on the activity level value at theoccurrence of the Ischemic episode or other event 512. Alternatively,the current detected patient physical activity level 508 may represent arunning average of the activity level when the ischemic episode or otherevent occurred. Over a predetermined period of time (e.g., several weeksor months), trends may be determined based on the heart activity history506, the patient physical activity level history 510, the time of day502 at which a detected heart activity and/or detected patient physicalactivity level is accompanied by an event, diagnostic history 514 and/orhistory of interaction/connection requests. These trends may indicateheart activities and patient physical activity level that are eitherlikely to trigger an event or prompt a patient to try establish aconnection between devices and time of day when events are more likelyto occur or a patient is more likely to attempt a connection betweendevices.

The announcement timing control module 222 may also access configurationdata, such as in the memory 94 and/or 494, that indicates preferencesregarding, for example, which announcement frequency factors 500override other factors 500, what levels detected by the interactionsensor 109 are to be interpreted as a physical tap by the patient, whatlevels of patient or heart activity are to be attained before theannouncement frequency is increased, how many different announcementfrequencies are to be employed, and so on.

FIG. 6 is a list of example announcement frequency modes 600 or statesthat the announcement timing control module 222 of FIGS. 1, 4A, and/or4B may provide based on the announcement frequency factors 500 of FIG.5. As shown in this particular example, three separate modes areutilized: a “fast” frequency mode 602, a “slow” frequency mode 604, andan “off” mode 606. In one implementation, the fast frequency mode 602may result in an announcement message, data packet, or other signalbeing transmitted via the telemetry circuit 424 once every 30 seconds,and the slow frequency mode 604 may result in an announcement frequencyof three minutes. In other embodiments, greater or fewer numbers ofannouncement frequency modes 600 may be employed, as well as differentannouncement frequencies for each of the modes 600. Moreover, someexamples may not implement the off mode 606 (during which noannouncement messages, data packets, or other signals are transmitted)unless an override mechanism, such as by way of a physical tap by thepatient, as described above, is available to initiate the wirelesscommunication connection 250 in the absence of an announcement.

FIG. 7 is an example state diagram 700 of the example announcementfrequency modes 600 of FIG. 6. In an example, the state diagram 700represents a state machine implemented within the announcement timingcontrol module 222. In the example of FIG. 7, the state machine may be aMoore state machine, in which the current announcement frequency isdictated by the current state or mode 602, 604, and 606. In otherexamples, a Mealy state machine may be implemented, in which the currentannouncement frequency associated with a specific state or mode 602,604, or 606 may be altered based on values of the announcement frequencyfactors 500.

The state diagram 700 includes several state transitions 702, 704, 706,708, 710, and 712 from one of the states 602, 604, and 606 to anotherbased on current values of the announcement frequency factors 500. Inother embodiments, one or more of the transitions 702-712 may beomitted. Also, in some embodiments, a transition from the off mode 606may be to either the slow mode 604 by way of transition 702 or to thefast mode 602 via transition 710, depending on the current state of oneor more of the announcement frequency factors 500. For example, theoccurrence of a clinical episode, as indicated by the current detectedevent 512, or the detection of a physical tap via the current detectedinteraction status 516, may cause the announcement timing control module222 to use transition 710 from the off mode 606 to the fast mode 602, orto use transition 704 from the slow mode 604 to the fast mode 602, tocreate a wireless communication connection 250 quickly. Similarly, atransition from the fast mode 602 may be to either the slow mode 604 byway of transition 706 or the off mode 606 via transition 712.

While the embodiments described in detail above focus on implantablemedical devices, other medical electronic devices that are notimplantable, such as a “wearable” medical device that may monitor forheart rate, arrhythmia and/or other medical conditions, may serve as theelectronic device 200, and may incorporate any of the aspects of theembodiments discussed above. Moreover, in some examples, the electronicdevice 200 may not be a medical device, whether implantable or not, butmay still incorporate one or more of the aspects of the embodimentsdescribed herein.

Those skilled in the art will understand and appreciate that variousmodifications not explicitly described above may be made to the presentdisclosure and still remain within the scope of the present invention.Moreover, although the present Invention has been described withreference to preferred embodiments, persons skilled in the art willrecognize that changes may be made in form and detail without departingfrom the scope of the present invention.

What is claimed is:
 1. An electronic device configured to communicatewirelessly with an external device separate from the electronic device,the electronic device comprising: a wireless communication interfaceconfigured to transmit announcement signals for creating a wirelesscommunication connection with the external device; a sensor configuredto detect a characteristic of an environment external to the electronicdevice; and a control circuit comprising an announcement timing controlmodule configured to dynamically control timing of the announcementsignals based on the detected characteristic.
 2. The electronic deviceof claim 1, the electronic device comprising at least one of anautomatic implantable cardioverter defibrillator, an artificial cardiacpacemaker, and an implantable loop recorder, and the detectedcharacteristic comprising an electrical signal produced by a heart of apatient.
 3. The electronic device of claim 1, wherein the detectedcharacteristic comprises a signal indicative of a patient's heartactivity.
 4. The electronic device of claim 1, further comprising areal-time clock configured to provide a current time of day, theannouncement timing control module further configured to dynamicallycontrol timing of the announcement signals based on both the detectedcharacteristic and on the current time of day.
 5. The electronic deviceof claim 4, wherein the sensor is at least one of an accelerometer and agyroscope.
 6. The electronic device of claim 4, wherein the detectedcharacteristic is a signal indicative of an activity level of a human.7. The electronic device of claim 6, wherein the announcement timingcontrol module is further configured to lower the frequency ofannouncement signals when the current time of day is an expected time ofsleep and the activity level is indicative of a supine posture.
 8. Animplantable medical device for monitoring physiology of a person, theimplantable medical device capable of wirelessly communicating with anexternal device located external to the person, the implantable medicaldevice comprising: a wireless communication interface configured totransmit announcement signals for creating a wireless communicationconnection with the external device; at least one sensor configured todetect a characteristic of an environment external to the implantablemedical device; and a control circuit comprising an announcement timingcontrol module configured to dynamically control timing of theannouncement signals based on at least the detected characteristic. 9.The implantable medical device of claim 8, the announcement signalscomprising announcement messages configured to dynamically vary thediscovery opportunities of the implantable medical device by theexternal device in a manner that will reduce current drain, theannouncement timing control module further configured to dynamicallycontrol the timing of the announcement messages by dynamically setting afrequency at which the announcement messages are repeatedly transmittedbased on at least the detected characteristic, the announcement timingcontrol module further configured to dynamically set the frequency to atleast one of a first frequency, and a second frequency slower than thefirst frequency.
 10. The implantable medical device of claim 8, furthercomprising a heart activity detector configured to determine a heartactivity of the person based on the detected characteristic, wherein theannouncement timing control module is configured to dynamically increaseor decrease the frequency of the announcement messages based on theheart activity.
 11. The implantable medical device of claim 8, theimplantable medical device configured to determine a heart rate of theperson based on the detected characteristic, wherein the announcementtiming control module is configured to increase the frequency of theannouncement messages in response to the determined heart rate exceedinga first threshold or falling below a second threshold.
 12. Theimplantable medical device of claim 8, the implantable medical deviceconfigured to determine, at least one of: a body position, and aphysical activity level of the person and whether the physical activitylevel of the person exceeds a threshold, wherein the announcement timingcontrol module is configured to increase the frequency of theannouncement messages in response to, at least one: the determined bodyposition being an upright position, and the determined physical activitylevel of the person exceeding a threshold.
 13. The implantable medicaldevice of claim 8, the implantable medical device configured todetermine, at least one of: a body position, and a physical activitylevel of the person, wherein the announcement timing control module isconfigured to cease transmission of the announcement messages inresponse to, at least one: the determined body position, and thedetermined physical activity level of the person indicating that theperson is sleeping.
 14. The implantable medical device of claim 10,wherein: the heart activity detector is further configured to detect anarrhythmia, the implantable device is configured to determine at leastone of a body position and a physical activity level of the person, andthe announcement timing control module is further configured todetermine whether the arrhythmia and the, at least one, body positionand physical activity level of the person indicate an exercise-inducedarrhythmia and Increase the frequency of the announcement messages whenan exercise-induced arrhythmia is determined.
 15. The implantablemedical device of claim 8, further comprising: a real-time clockconfigured to provide a current time of day, the announcement timingcontrol module further configured to dynamically set the frequency ofthe announcement messages based on the current time of day.
 16. Theimplantable medical device of claim 8, further comprising: a heartactivity detector configured to determine a heart activity of the personbased on the detected characteristic; a memory configured to store aheart activity together with the time of day at which the heart activitywas detected; and a microcontroller configured to determine a trend inthe time of day at which pathological heart activity is detected,wherein the announcement timing control module is further configured todynamically set the frequency of the announcement messages based thetrend.
 17. The implantable medical device of claim 8, furthercomprising: a heart activity detector configured to determine a heartactivity of the person and determine whether the heart activity is apathological heart activity based on the detected characteristic; anevent detector configured to detect a cardiac event; a memory configuredto store at least one of the pathological heart activity and the cardiacevent together with the time of day at which at least one of thepathological heart activity and the cardiac event was detected; and amicrocontroller configured to determine a trend in the time of day atwhich at least one of the pathological heart activity and cardiac eventis detected, wherein the announcement timing control module is furtherconfigured to dynamically set the frequency of the announcement messagesbased on the trend.
 18. The implantable medical device of claim 8,further comprising: a heart activity detector configured to determine aheart activity of the person based on the detected characteristic; anevent detector configured to detect cardiac events; a memory configuredto store at least one of the heart activity and cardiac event when theperson triggers the implantable medical device to connect with anexternal device; a microcontroller configured to determine a trend in atleast one of the heart activity and the cardiac event occurring when theperson triggers the implantable medical device to connect with theexternal device, wherein the announcement timing control module isfurther configured to increase the frequency of the announcementmessages when at least one of a current detected heart activity and acurrent detected cardiac event satisfies the trend.
 19. The implantablemedical device of claim 8, further comprising: a sensor configured todetect a level of acceleration imparted upon the implantable medicaldevice, the announcement timing control module further configured toincrease the frequency of the announcement messages based on thedetected level of acceleration exceeding a threshold.
 20. A method fordynamically controlling a frequency of advertising messages transmittedby an electronic device to create a wireless communication connectionwith an external device separate from the electronic device, the methodcomprising: detecting a characteristic of an environment external to theelectronic device; accessing an advertising frequency factor employableto set a frequency of advertising messages, wherein the advertisingfrequency factor is based on the detected characteristic; setting afrequency of the advertising messages based at least in part on theadvertising frequency factor; and transmitting the advertising messagesusing the frequency.
 21. The method of claim 20, the announcementfrequency factor comprising a heart rate of a patient.
 23. The method ofclaim 20, the announcement frequency factor comprising at least one of acardiac and neurogenic event of a patient.
 23. The method of claim 20,the announcement frequency factor comprising at least one of a bodyposition and a physical activity level of a patient.
 24. The method ofclaim 23, further comprising providing a current time of day using areal-time clock, wherein setting a frequency of the advertising messagesbased at least in part on the advertising frequency factor comprisessetting a frequency of the advertising messages based on the at leastone body position and physical activity level of the patient and thecurrent time of day.